1.5.0-alpha1 Revision Graph Bug?

I just installed TortoiseSVN 1.5.0-alpha1 win32 version to give it a test. I opened up a revision graph for a working copy (one created by an earlier version of Tortoise, 1.4.7 I believe) and saw the graph shown in the screenshot RevisionGraph-Before.bmp. I unchecked the "Groups Branches Together" tool button, and got the result shown in screenshot RevisionGraph-After.bmp. There was no way for me to reach that second tag node at the top of the window. I've included the screenshots below.